Ever wondered how ocean currents affect climate? Ocean currents are a continuous and directed movement of the ocean water. This happens through forces acting on the water, such as difference in salinity, the waves breaking, temperature, the wind or even the Coriolis effect. The direction of the current is determined by the depth of the contours, other currents acting on the ocean and the nature of the shoreline.
The currents will travel thousands of kilometers, in the process establishing a conveyer belt globally that brings about different climatic conditions across the world. The currents will either act above the surface of the ocean, or deep below the surface of the ocean (at least 300 meters). Depending on the cause, ocean currents will move vertically or horizontally, and they can also be influenced by the land masses that border the ocean, the topography or the shape of the ocean basin.
As the horizontal currents are moving south or northwards, they carry with them cool or warm water over an extended distance. It is the displaced water that affects the air, by warming or cooling it, thereby transferring the same effect to the land surface over which it blows. This is how ocean currents affect climate.
Cold ocean currents are large masses of cold water that move towards the equator, from a level of high altitude to lower levels. They absorb the heat they receive in the tropics, thereby cooling the air above them. The cold currents often form when the air on the subtropical high blows over a cold mass of water, then the cold air is dragged to the equator.
Warm currents, on the other hand, are large masses of warm water moving further away from the equator, at higher temperatures. They form when salty cold water becomes heavy and sinks, in the process forcing warm and lighter water to move in the opposite direction.
The influence of the flow of currents usually depends on the level of saltiness of the water, the rotation of the earth, the topography of the land and the orientation of the wind. It is these that bring cold water to the surface of the earth from the depths, and in the process forcing away the original surface water. It is because of this reason that you will always notice that the ocean is often cooler to the eastern coastal side than the western coastal side.